1. Field of the Invention
This invention relates to opening tools for containers, popularly known as pop top cans, having tear-away closures at one end, it particularly relates to opening tools that comprise a curved cam used as a rolling fulcrum member for removing such closures.
2. Review of the Prior Art
The closure panel of a pop top can is generally disposed in the top end of the container and is defined and surrounded by a score line which is disposed close to the upstanding side of the container. A ring tab, lying flush with the surface of the closure panel, is connected to the panel at one end by a rivet which is close to the score line.
The container is opened by inserting a finger-type member or prong under the free end of the ring tab to tilt the tab upwardly and cause the riveted end to break the closure panel at the adjacent score line. Then the prong is inserted into the opening of the ring tab, and a pulling force is exerted to pull the ring tab upwardly and away from the top of the container so that the closure panel is initially peeled back and then pulled completely away from the top end of the container.
If the container is made of aluminum, this conventional opening procedure is relatively easy and causes almost no problems. However, if the container is made of steel, as is generally the situation, it may cause many problems, such as broken fingernails and cuts in fingers of children and people having average strength. In addition, repeated opening of these cans causes weariness of people, such as waitresses, who must open such containers frequently. Furthermore, children, elderly people, and people afflicted with arthritis may be so weak that they are unable to open the containers or even to lift the ring tab. There is consequently a need for a device that can provide a simple and nearly effortless procedure for opening such pop top cans.
U.S. Pat. No. 4,362,071 of J. M. Coker discloses a can opener that is primarily intended for a can having a tab-type closure of the type used on beer and soft drink cans, but the device can also be used on cans having the rivet adjacent to the score line of a tear-away closure. The opener comprises a mouth located rearwardly of a gap in one end, a handle as its other end, and treads disposed transversely along its convex mid portion. When a ring tab is caught in the mouth and the handle is depressed downwardly, the treads engage the rim of the can and prevent slippage during pivoting of the opener.
U.S. Pat. No. 5,018,409 of J. A. Bittel describes a tear top can opener for opening the closure panel of a container having a pull ring located adjacent the peripheral edge of the container. The opener comprises a handle, an opener end formed with a prong perpendicular to the longitudinal axis of the opener for engaging the pull ring, and a bulbous body having a parabolic shaped edge for allowing the opener to be pivoted on the container in order to lift the pull ring vertically for opening the closure.
Des. 240,188 of R. R. Lytle shows a combined can and bottle opener which comprises an elongated handle attached at one end to a circular portion that has a rearwardly extending hook.
Des. 267,925 of M. R. La Mancusa shows a combined bottle opener and can opener which comprises an elongated portion and a rounded portion at one end that terminates in a large, rearwardly extending pointed member.
Des. 297,705 of J. Difede shows a hook opener for jug lids or the like, comprising a hook which leads to a gently curved surface.
Although most of these devices utilize a rounded portion or a convexly curved surface as a fulcrum member for lifting a ring tab attached to the end of a container, they do not continue to use a rolling surface for completely peeling away the closure. All utilize a fixed fulcrum member or require an upward pulling force to be exerted in order to remove the closure panel completely.
The Coker device utilizes one of its treads to provide a fixed fulcrum member. The Bittel device cannot continue to utilize its rolling surface because its handle engages the rim of the can as a fixed fulcrum for the final lifting movement. The rounded ends of the devices shown in the Lytle and La Mancusa design patents can be utilized as rolling surfaces for limited lifting, but the devices must then be pulled upwardly without leverage in order to remove the closure panel from the container. The device shown in the Difede design patent apparently utilizes its curved surface as a fixed fulcrumming point, at the point of contact with a jug lid, for lifting the edge of the lid with the hook.
There is consequently a need for a can opener for pop top cans that utilizes a rolling surface throughout its contact with the closure panel and up to and beyond contact with the rim of the can, in order to minimize the effort required for pulling the closure panel forcibly but easily away from the can. Such a rolling surface must provide maximum lift for breaking the seal and then for initial separation along the immediately adjacent score line. Moreover, there is also a need for a device that is adapted to be packaged with a cylindrical can in a space saving manner while providing a convenient gripping means and requiring a small quantity of material for manufacture thereof.